[PATCH] general style: replaces memcmp() with starts_with()

[PATCH] general style: replaces memcmp() with starts_with()

[Quint Guvernator]

memcmp() is replaced with starts_with() when comparing strings from the
beginning. starts_with() looks nicer and it saves the extra argument of
the length of the comparing string.

Signed-off-by: Quint Guvernator <quintus.public@gmail.com>
---
 builtin/apply.c                           | 10 +++++-----
 builtin/cat-file.c                        |  2 +-
 builtin/commit-tree.c                     |  2 +-
 builtin/for-each-ref.c                    |  2 +-
 builtin/get-tar-commit-id.c               |  2 +-
 builtin/mailinfo.c                        | 10 +++++-----
 builtin/mktag.c                           |  8 ++++----
 builtin/patch-id.c                        | 18 +++++++++---------
 commit.c                                  | 18 +++++++++---------
 connect.c                                 |  8 ++++----
 contrib/convert-objects/convert-objects.c |  6 +++---
 convert.c                                 |  2 +-
 credential-cache.c                        |  2 +-
 fetch-pack.c                              |  2 +-
 fsck.c                                    |  8 ++++----
 http-walker.c                             |  4 ++--
 imap-send.c                               |  2 +-
 pack-write.c                              |  2 +-
 path.c                                    |  2 +-
 refs.c                                    |  2 +-
 remote.c                                  |  2 +-
 submodule.c                               |  2 +-
 transport.c                               |  2 +-
 xdiff-interface.c                         |  2 +-
 24 files changed, 60 insertions(+), 60 deletions(-)

diff --git a/builtin/apply.c b/builtin/apply.c
index a7e72d5..8f21957 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -846,8 +846,8 @@ static int has_epoch_timestamp(const char *nameline)
 	 * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
 	 * (west of GMT) or 1970-01-01 (east of GMT)
 	 */
-	if ((zoneoffset < 0 && memcmp(timestamp, "1969-12-31", 10)) ||
-	    (0 <= zoneoffset && memcmp(timestamp, "1970-01-01", 10)))
+	if ((zoneoffset < 0 && starts_with(timestamp, "1969-12-31")) ||
+	    (0 <= zoneoffset && starts_with(timestamp, "1970-01-01")))
 		return 0;
 
 	hourminute = (strtol(timestamp + 11, NULL, 10) * 60 +
@@ -1631,7 +1631,7 @@ static int parse_fragment(const char *line, unsigned long size,
 		 * l10n of "\ No newline..." is at least that long.
 		 */
 		case '\\':
-			if (len < 12 || memcmp(line, "\\ ", 2))
+			if (len < 12 || starts_with(line, "\\ "))
 				return -1;
 			break;
 		}
@@ -1646,7 +1646,7 @@ static int parse_fragment(const char *line, unsigned long size,
 	 * it in the above loop because we hit oldlines == newlines == 0
 	 * before seeing it.
 	 */
-	if (12 < size && !memcmp(line, "\\ ", 2))
+	if (12 < size && !starts_with(line, "\\ "))
 		offset += linelen(line, size);
 
 	patch->lines_added += added;
@@ -1673,7 +1673,7 @@ static int parse_single_patch(const char *line, unsigned long size, struct patch
 	unsigned long oldlines = 0, newlines = 0, context = 0;
 	struct fragment **fragp = &patch->fragments;
 
-	while (size > 4 && !memcmp(line, "@@ -", 4)) {
+	while (size > 4 && !starts_with(line, "@@ -")) {
 		struct fragment *fragment;
 		int len;
 
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index d5a93e0..be83345 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -82,7 +82,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 				enum object_type type;
 				unsigned long size;
 				char *buffer = read_sha1_file(sha1, &type, &size);
-				if (memcmp(buffer, "object ", 7) ||
+				if (starts_with(buffer, "object ") ||
 				    get_sha1_hex(buffer + 7, blob_sha1))
 					die("%s not a valid tag", sha1_to_hex(sha1));
 				free(buffer);
diff --git a/builtin/commit-tree.c b/builtin/commit-tree.c
index 987a4c3..2d995a2 100644
--- a/builtin/commit-tree.c
+++ b/builtin/commit-tree.c
@@ -66,7 +66,7 @@ int cmd_commit_tree(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		if (!memcmp(arg, "-S", 2)) {
+		if (!starts_with(arg, "-S")) {
 			sign_commit = arg + 2;
 			continue;
 		}
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 51798b4..be14d71 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -193,7 +193,7 @@ static int verify_format(const char *format)
 		at = parse_atom(sp + 2, ep);
 		cp = ep + 1;
 
-		if (!memcmp(used_atom[at], "color:", 6))
+		if (!starts_with(used_atom[at], "color:"))
 			need_color_reset_at_eol = !!strcmp(used_atom[at], color_reset);
 	}
 	return 0;
diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index aa72596..d645525 100644
--- a/builtin/get-tar-commit-id.c
+++ b/builtin/get-tar-commit-id.c
@@ -29,7 +29,7 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
 		die("git get-tar-commit-id: read error");
 	if (header->typeflag[0] != 'g')
 		return 1;
-	if (memcmp(content, "52 comment=", 11))
+	if (starts_with(content, "52 comment="))
 		return 1;
 
 	n = write_in_full(1, content + 11, 41);
diff --git a/builtin/mailinfo.c b/builtin/mailinfo.c
index 2c3cd8e..63f0230 100644
--- a/builtin/mailinfo.c
+++ b/builtin/mailinfo.c
@@ -626,7 +626,7 @@ static int handle_boundary(void)
 	strbuf_addch(&newline, '\n');
 again:
 	if (line.len >= (*content_top)->len + 2 &&
-	    !memcmp(line.buf + (*content_top)->len, "--", 2)) {
+	    !starts_with(line.buf + (*content_top)->len, "--")) {
 		/* we hit an end boundary */
 		/* pop the current boundary off the stack */
 		strbuf_release(*content_top);
@@ -727,8 +727,8 @@ static int is_scissors_line(const struct strbuf *line)
 			continue;
 		}
 		if (i + 1 < len &&
-		    (!memcmp(buf + i, ">8", 2) || !memcmp(buf + i, "8<", 2) ||
-		     !memcmp(buf + i, ">%", 2) || !memcmp(buf + i, "%<", 2))) {
+		    (!starts_with(buf + i, ">8") || !starts_with(buf + i, "8<") ||
+		     !starts_with(buf + i, ">%") || !starts_with(buf + i, "%<"))) {
 			in_perforation = 1;
 			perforation += 2;
 			scissors += 2;
@@ -929,13 +929,13 @@ static void handle_info(void)
 		else
 			continue;
 
-		if (!memcmp(header[i], "Subject", 7)) {
+		if (!starts_with(header[i], "Subject")) {
 			if (!keep_subject) {
 				cleanup_subject(hdr);
 				cleanup_space(hdr);
 			}
 			output_header_lines(fout, "Subject", hdr);
-		} else if (!memcmp(header[i], "From", 4)) {
+		} else if (!starts_with(header[i], "From")) {
 			cleanup_space(hdr);
 			handle_from(hdr);
 			fprintf(fout, "Author: %s\n", name.buf);
diff --git a/builtin/mktag.c b/builtin/mktag.c
index 640ab64..54ec4e1 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -49,7 +49,7 @@ static int verify_tag(char *buffer, unsigned long size)
 
 	/* Verify object line */
 	object = buffer;
-	if (memcmp(object, "object ", 7))
+	if (starts_with(object, "object "))
 		return error("char%d: does not start with \"object \"", 0);
 
 	if (get_sha1_hex(object + 7, sha1))
@@ -57,7 +57,7 @@ static int verify_tag(char *buffer, unsigned long size)
 
 	/* Verify type line */
 	type_line = object + 48;
-	if (memcmp(type_line - 1, "\ntype ", 6))
+	if (starts_with(type_line - 1, "\ntype "))
 		return error("char%d: could not find \"\\ntype \"", 47);
 
 	/* Verify tag-line */
@@ -66,7 +66,7 @@ static int verify_tag(char *buffer, unsigned long size)
 		return error("char%"PRIuMAX": could not find next \"\\n\"",
 				(uintmax_t) (type_line - buffer));
 	tag_line++;
-	if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
+	if (starts_with(tag_line, "tag ") || tag_line[4] == '\n')
 		return error("char%"PRIuMAX": no \"tag \" found",
 				(uintmax_t) (tag_line - buffer));
 
@@ -98,7 +98,7 @@ static int verify_tag(char *buffer, unsigned long size)
 	/* Verify the tagger line */
 	tagger_line = tag_line;
 
-	if (memcmp(tagger_line, "tagger ", 7))
+	if (starts_with(tagger_line, "tagger "))
 		return error("char%"PRIuMAX": could not find \"tagger \"",
 			(uintmax_t) (tagger_line - buffer));
 
diff --git a/builtin/patch-id.c b/builtin/patch-id.c
index 3cfe02d..cc10f1d 100644
--- a/builtin/patch-id.c
+++ b/builtin/patch-id.c
@@ -66,13 +66,13 @@ static int get_one_patchid(unsigned char *next_sha1, git_SHA_CTX *ctx, struct st
 		char *p = line;
 		int len;
 
-		if (!memcmp(line, "diff-tree ", 10))
+		if (!starts_with(line, "diff-tree "))
 			p += 10;
-		else if (!memcmp(line, "commit ", 7))
+		else if (!starts_with(line, "commit "))
 			p += 7;
-		else if (!memcmp(line, "From ", 5))
+		else if (!starts_with(line, "From "))
 			p += 5;
-		else if (!memcmp(line, "\\ ", 2) && 12 < strlen(line))
+		else if (!starts_with(line, "\\ ") && 12 < strlen(line))
 			continue;
 
 		if (!get_sha1_hex(p, next_sha1)) {
@@ -81,14 +81,14 @@ static int get_one_patchid(unsigned char *next_sha1, git_SHA_CTX *ctx, struct st
 		}
 
 		/* Ignore commit comments */
-		if (!patchlen && memcmp(line, "diff ", 5))
+		if (!patchlen && starts_with(line, "diff "))
 			continue;
 
 		/* Parsing diff header?  */
 		if (before == -1) {
-			if (!memcmp(line, "index ", 6))
+			if (!starts_with(line, "index "))
 				continue;
-			else if (!memcmp(line, "--- ", 4))
+			else if (!starts_with(line, "--- "))
 				before = after = 1;
 			else if (!isalpha(line[0]))
 				break;
@@ -96,14 +96,14 @@ static int get_one_patchid(unsigned char *next_sha1, git_SHA_CTX *ctx, struct st
 
 		/* Looking for a valid hunk header?  */
 		if (before == 0 && after == 0) {
-			if (!memcmp(line, "@@ -", 4)) {
+			if (!starts_with(line, "@@ -")) {
 				/* Parse next hunk, but ignore line numbers.  */
 				scan_hunk_header(line, &before, &after);
 				continue;
 			}
 
 			/* Split at the end of the patch.  */
-			if (memcmp(line, "diff ", 5))
+			if (starts_with(line, "diff "))
 				break;
 
 			/* Else we're parsing another header.  */
diff --git a/commit.c b/commit.c
index 6bf4fe0..b259c17 100644
--- a/commit.c
+++ b/commit.c
@@ -90,13 +90,13 @@ static unsigned long parse_commit_date(const char *buf, const char *tail)
 
 	if (buf + 6 >= tail)
 		return 0;
-	if (memcmp(buf, "author", 6))
+	if (starts_with(buf, "author"))
 		return 0;
 	while (buf < tail && *buf++ != '\n')
 		/* nada */;
 	if (buf + 9 >= tail)
 		return 0;
-	if (memcmp(buf, "committer", 9))
+	if (starts_with(buf, "committer"))
 		return 0;
 	while (buf < tail && *buf++ != '>')
 		/* nada */;
@@ -269,7 +269,7 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
 		return 0;
 	item->object.parsed = 1;
 	tail += size;
-	if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
+	if (tail <= bufptr + 46 || starts_with(bufptr, "tree ") || bufptr[45] != '\n')
 		return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
 	if (get_sha1_hex(bufptr + 5, parent) < 0)
 		return error("bad tree pointer in commit %s",
@@ -279,7 +279,7 @@ int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long s
 	pptr = &item->parents;
 
 	graft = lookup_commit_graft(item->object.sha1);
-	while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
+	while (bufptr + 48 < tail && !starts_with(bufptr, "parent ")) {
 		struct commit *new_parent;
 
 		if (tail <= bufptr + 48 ||
@@ -1279,11 +1279,11 @@ struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
 
 static inline int standard_header_field(const char *field, size_t len)
 {
-	return ((len == 4 && !memcmp(field, "tree ", 5)) ||
-		(len == 6 && !memcmp(field, "parent ", 7)) ||
-		(len == 6 && !memcmp(field, "author ", 7)) ||
-		(len == 9 && !memcmp(field, "committer ", 10)) ||
-		(len == 8 && !memcmp(field, "encoding ", 9)));
+	return ((len == 4 && !starts_with(field, "tree ")) ||
+		(len == 6 && !starts_with(field, "parent ")) ||
+		(len == 6 && !starts_with(field, "author ")) ||
+		(len == 9 && !starts_with(field, "committer ")) ||
+		(len == 8 && !starts_with(field, "encoding ")));
 }
 
 static int excluded_header_field(const char *field, size_t len, const char **exclude)
diff --git a/connect.c b/connect.c
index 4150412..4cb1c7c 100644
--- a/connect.c
+++ b/connect.c
@@ -18,7 +18,7 @@ static int check_ref(const char *name, int len, unsigned int flags)
 	if (!flags)
 		return 1;
 
-	if (len < 5 || memcmp(name, "refs/", 5))
+	if (len < 5 || starts_with(name, "refs/"))
 		return 0;
 
 	/* Skip the "refs/" part */
@@ -30,11 +30,11 @@ static int check_ref(const char *name, int len, unsigned int flags)
 		return 0;
 
 	/* REF_HEADS means that we want regular branch heads */
-	if ((flags & REF_HEADS) && !memcmp(name, "heads/", 6))
+	if ((flags & REF_HEADS) && !starts_with(name, "heads/"))
 		return 1;
 
 	/* REF_TAGS means that we want tags */
-	if ((flags & REF_TAGS) && !memcmp(name, "tags/", 5))
+	if ((flags & REF_TAGS) && !starts_with(name, "tags/"))
 		return 1;
 
 	/* All type bits clear means that we are ok with anything */
@@ -514,7 +514,7 @@ static int git_proxy_command_options(const char *var, const char *value,
 		if (0 <= matchlen) {
 			/* core.gitproxy = none for kernel.org */
 			if (matchlen == 4 &&
-			    !memcmp(value, "none", 4))
+			    !starts_with(value, "none"))
 				matchlen = 0;
 			git_proxy_command = xmemdupz(value, matchlen);
 		}
diff --git a/contrib/convert-objects/convert-objects.c b/contrib/convert-objects/convert-objects.c
index f3b57bf..72914e1 100644
--- a/contrib/convert-objects/convert-objects.c
+++ b/contrib/convert-objects/convert-objects.c
@@ -245,7 +245,7 @@ static void convert_date(void *buffer, unsigned long size, unsigned char *result
 	size -= 46;
 
 	/* "parent <sha1>\n" */
-	while (!memcmp(buffer, "parent ", 7)) {
+	while (!starts_with(buffer, "parent ")) {
 		memcpy(new + newlen, buffer, 48);
 		newlen += 48;
 		buffer = (char *) buffer + 48;
@@ -270,11 +270,11 @@ static void convert_commit(void *buffer, unsigned long size, unsigned char *resu
 	void *orig_buffer = buffer;
 	unsigned long orig_size = size;
 
-	if (memcmp(buffer, "tree ", 5))
+	if (starts_with(buffer, "tree "))
 		die("Bad commit '%s'", (char *) buffer);
 	convert_ascii_sha1((char *) buffer + 5);
 	buffer = (char *) buffer + 46;    /* "tree " + "hex sha1" + "\n" */
-	while (!memcmp(buffer, "parent ", 7)) {
+	while (!starts_with(buffer, "parent ")) {
 		convert_ascii_sha1((char *) buffer + 7);
 		buffer = (char *) buffer + 48;
 	}
diff --git a/convert.c b/convert.c
index ab80b72..8f0b1bd 100644
--- a/convert.c
+++ b/convert.c
@@ -543,7 +543,7 @@ static int ident_to_git(const char *path, const char *src, size_t len,
 		len -= dollar + 1 - src;
 		src  = dollar + 1;
 
-		if (len > 3 && !memcmp(src, "Id:", 3)) {
+		if (len > 3 && !starts_with(src, "Id:")) {
 			dollar = memchr(src + 3, '$', len - 3);
 			if (!dollar)
 				break;
diff --git a/credential-cache.c b/credential-cache.c
index 9a03792..0b55946 100644
--- a/credential-cache.c
+++ b/credential-cache.c
@@ -54,7 +54,7 @@ static void spawn_daemon(const char *socket)
 	r = read_in_full(daemon.out, buf, sizeof(buf));
 	if (r < 0)
 		die_errno("unable to read result code from cache daemon");
-	if (r != 3 || memcmp(buf, "ok\n", 3))
+	if (r != 3 || starts_with(buf, "ok\n"))
 		die("cache daemon did not start: %.*s", r, buf);
 	close(daemon.out);
 }
diff --git a/fetch-pack.c b/fetch-pack.c
index f061f1f..10abe9e 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -506,7 +506,7 @@ static void filter_refs(struct fetch_pack_args *args,
 		int keep = 0;
 		next = ref->next;
 
-		if (!memcmp(ref->name, "refs/", 5) &&
+		if (!starts_with(ref->name, "refs/") &&
 		    check_refname_format(ref->name, 0))
 			; /* trash */
 		else {
diff --git a/fsck.c b/fsck.c
index 99c0497..10b70ca 100644
--- a/fsck.c
+++ b/fsck.c
@@ -290,12 +290,12 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
 	if (commit->date == ULONG_MAX)
 		return error_func(&commit->object, FSCK_ERROR, "invalid author/committer line");
 
-	if (memcmp(buffer, "tree ", 5))
+	if (starts_with(buffer, "tree "))
 		return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'tree' line");
 	if (get_sha1_hex(buffer+5, tree_sha1) || buffer[45] != '\n')
 		return error_func(&commit->object, FSCK_ERROR, "invalid 'tree' line format - bad sha1");
 	buffer += 46;
-	while (!memcmp(buffer, "parent ", 7)) {
+	while (!starts_with(buffer, "parent ")) {
 		if (get_sha1_hex(buffer+7, sha1) || buffer[47] != '\n')
 			return error_func(&commit->object, FSCK_ERROR, "invalid 'parent' line format - bad sha1");
 		buffer += 48;
@@ -322,13 +322,13 @@ static int fsck_commit(struct commit *commit, fsck_error error_func)
 		if (p || parents)
 			return error_func(&commit->object, FSCK_ERROR, "parent objects missing");
 	}
-	if (memcmp(buffer, "author ", 7))
+	if (starts_with(buffer, "author "))
 		return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'author' line");
 	buffer += 7;
 	err = fsck_ident(&buffer, &commit->object, error_func);
 	if (err)
 		return err;
-	if (memcmp(buffer, "committer ", strlen("committer ")))
+	if (starts_with(buffer, "committer "))
 		return error_func(&commit->object, FSCK_ERROR, "invalid format - expected 'committer' line");
 	buffer += strlen("committer ");
 	err = fsck_ident(&buffer, &commit->object, error_func);
diff --git a/http-walker.c b/http-walker.c
index 1516c5e..9ffe05e 100644
--- a/http-walker.c
+++ b/http-walker.c
@@ -245,7 +245,7 @@ static void process_alternates_response(void *callback_data)
 						     - base);
 					okay = 1;
 				}
-			} else if (!memcmp(data + i, "../", 3)) {
+			} else if (!starts_with(data + i, "../")) {
 				/*
 				 * Relative URL; chop the corresponding
 				 * number of subpath from base (and ../
@@ -267,7 +267,7 @@ static void process_alternates_response(void *callback_data)
 				i += 3;
 				serverlen = strlen(base);
 				while (i + 2 < posn &&
-				       !memcmp(data + i, "../", 3)) {
+				       !starts_with(data + i, "../")) {
 					do {
 						serverlen--;
 					} while (serverlen &&
diff --git a/imap-send.c b/imap-send.c
index 0bc6f7f..334b425 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -802,7 +802,7 @@ static int get_cmd_result(struct imap_store *ctx, struct imap_cmd *tcmd)
 				resp = DRV_OK;
 			else {
 				if (!strcmp("NO", arg)) {
-					if (cmdp->cb.create && cmd && (cmdp->cb.trycreate || !memcmp(cmd, "[TRYCREATE]", 11))) { /* SELECT, APPEND or UID COPY */
+					if (cmdp->cb.create && cmd && (cmdp->cb.trycreate || !starts_with(cmd, "[TRYCREATE]"))) { /* SELECT, APPEND or UID COPY */
 						p = strchr(cmdp->cmd, '"');
 						if (!issue_imap_cmd(ctx, NULL, "CREATE \"%.*s\"", (int)(strchr(p + 1, '"') - p + 1), p)) {
 							resp = RESP_BAD;
diff --git a/pack-write.c b/pack-write.c
index 9b8308b..6f58024 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -289,7 +289,7 @@ char *index_pack_lockfile(int ip_out)
 	 * later on.  If we don't get that then tough luck with it.
 	 */
 	if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
-	    memcmp(packname, "keep\t", 5) == 0) {
+	    starts_with(packname, "keep\t") == 0) {
 		char path[PATH_MAX];
 		packname[45] = 0;
 		snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
diff --git a/path.c b/path.c
index f9c5062..23f8437 100644
--- a/path.c
+++ b/path.c
@@ -26,7 +26,7 @@ static char *get_pathname(void)
 static char *cleanup_path(char *path)
 {
 	/* Clean it up */
-	if (!memcmp(path, "./", 2)) {
+	if (!starts_with(path, "./")) {
 		path += 2;
 		while (*path == '/')
 			path++;
diff --git a/refs.c b/refs.c
index 89228e2..b5a14e3 100644
--- a/refs.c
+++ b/refs.c
@@ -63,7 +63,7 @@ static int check_refname_component(const char *refname, int flags)
 		if (refname[1] == '\0')
 			return -1; /* Component equals ".". */
 	}
-	if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
+	if (cp - refname >= 5 && !starts_with(cp - 5, ".lock"))
 		return -1; /* Refname ends with ".lock". */
 	return cp - refname;
 }
diff --git a/remote.c b/remote.c
index e41251e..0b8986a 100644
--- a/remote.c
+++ b/remote.c
@@ -1144,7 +1144,7 @@ static int match_explicit(struct ref *src, struct ref *dst,
 	case 1:
 		break;
 	case 0:
-		if (!memcmp(dst_value, "refs/", 5))
+		if (!starts_with(dst_value, "refs/"))
 			matched_dst = make_linked_ref(dst_value, dst_tail);
 		else if (is_null_sha1(matched_src->new_sha1))
 			error("unable to delete '%s': remote ref does not exist",
diff --git a/submodule.c b/submodule.c
index b80ecac..1edebc1 100644
--- a/submodule.c
+++ b/submodule.c
@@ -203,7 +203,7 @@ void gitmodules_config(void)
 			if (active_nr > pos) {  /* there is a .gitmodules */
 				const struct cache_entry *ce = active_cache[pos];
 				if (ce_namelen(ce) == 11 &&
-				    !memcmp(ce->name, ".gitmodules", 11))
+				    !starts_with(ce->name, ".gitmodules"))
 					gitmodules_is_unmerged = 1;
 			}
 		} else if (pos < active_nr) {
diff --git a/transport.c b/transport.c
index ca7bb44..c4b3ac9 100644
--- a/transport.c
+++ b/transport.c
@@ -1364,7 +1364,7 @@ static int refs_from_alternate_cb(struct alternate_object_database *e,
 
 	while (other[len-1] == '/')
 		other[--len] = '\0';
-	if (len < 8 || memcmp(other + len - 8, "/objects", 8))
+	if (len < 8 || starts_with(other + len - 8, "/objects"))
 		return 0;
 	/* Is this a git repository with refs? */
 	memcpy(other + len - 8, "/refs", 6);
diff --git a/xdiff-interface.c b/xdiff-interface.c
index ecfa05f..4be401d 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -53,7 +53,7 @@ int parse_hunk_header(char *line, int len,
 	}
 	else
 		*nn = 1;
-	return -!!memcmp(cp, " @@", 3);
+	return -!!starts_with(cp, " @@");
 }
 
 static void consume_one(void *priv_, char *s, unsigned long size)
-- 
1.9.0

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Duy Nguyen]

On Wed, Mar 12, 2014 at 8:44 PM, Quint Guvernator
<quintus.public@gmail.com> wrote:
> diff --git a/builtin/apply.c b/builtin/apply.c
> index a7e72d5..8f21957 100644
> --- a/builtin/apply.c
> +++ b/builtin/apply.c
> @@ -846,8 +846,8 @@ static int has_epoch_timestamp(const char *nameline)
>          * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
>          * (west of GMT) or 1970-01-01 (east of GMT)
>          */
> -       if ((zoneoffset < 0 && memcmp(timestamp, "1969-12-31", 10)) ||
> -           (0 <= zoneoffset && memcmp(timestamp, "1970-01-01", 10)))
> +       if ((zoneoffset < 0 && starts_with(timestamp, "1969-12-31")) ||
> +           (0 <= zoneoffset && starts_with(timestamp, "1970-01-01")))
>                 return 0;

It is not a plain search/replace. starts_with(..) == !memcmp(...). So
you need to negate every replacement.
-- 
Duy

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Quint Guvernator]

2014-03-12 9:51 GMT-04:00 Duy Nguyen <pclouds@gmail.com>:
> starts_with(..) == !memcmp(...). So
> you need to negate every replacement.

My apologies--it doesn't look like the tests caught it either. I will
fix this and submit a new patch.

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Jens Lehmann]

Am 12.03.2014 14:44, schrieb Quint Guvernator:
> memcmp() is replaced with starts_with() when comparing strings from the
> beginning. starts_with() looks nicer and it saves the extra argument of
> the length of the comparing string.
> 
> Signed-off-by: Quint Guvernator <quintus.public@gmail.com>
> ---

...

> diff --git a/submodule.c b/submodule.c
> index b80ecac..1edebc1 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -203,7 +203,7 @@ void gitmodules_config(void)
>  			if (active_nr > pos) {  /* there is a .gitmodules */
>  				const struct cache_entry *ce = active_cache[pos];
>  				if (ce_namelen(ce) == 11 &&
> -				    !memcmp(ce->name, ".gitmodules", 11))
> +				    !starts_with(ce->name, ".gitmodules"))
>  					gitmodules_is_unmerged = 1;
>  			}
>  		} else if (pos < active_nr) {

I think this hunk should be dropped as the memcmp() here doesn't mean
"starts with" but "is identical" (due to the "ce_namelen(ce) == 11" in
the line above).

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Quint Guvernator]

2014-03-12 11:47 GMT-04:00 Jens Lehmann <Jens.Lehmann@web.de>:
> I think this hunk should be dropped as the memcmp() here doesn't mean
> "starts with" but "is identical" (due to the "ce_namelen(ce) == 11" in
> the line above).

There is an issue with negation in this patch. I've submitted a new
one [1] to the mailing list. The subject line of the new patch is
"[PATCH] general style: replaces memcmp() with proper starts_with()".

Let me know if you still think the hunk should be dropped there.

[1]: http://thread.gmane.org/gmane.comp.version-control.git/243940

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Jens Lehmann]

Am 12.03.2014 17:46, schrieb Quint Guvernator:
> 2014-03-12 11:47 GMT-04:00 Jens Lehmann <Jens.Lehmann@web.de>:
>> I think this hunk should be dropped as the memcmp() here doesn't mean
>> "starts with" but "is identical" (due to the "ce_namelen(ce) == 11" in
>> the line above).
> 
> There is an issue with negation in this patch. I've submitted a new
> one [1] to the mailing list. The subject line of the new patch is
> "[PATCH] general style: replaces memcmp() with proper starts_with()".

Thanks, I missed that one (please use "[PATCH v2]" in the subject
line of a second patch to make follow-ups easily distinguishable
from the initial one ;-).

> Let me know if you still think the hunk should be dropped there.

Yes, I think so. That spot uses memcmp() because ce->name may
not be 0-terminated. If that assumption isn't correct, it should
be replaced with a plain strcmp() instead (while also dropping
the ce_namelen() comparison in the line above). But starts_with()
points into the wrong direction there.

> [1]: http://thread.gmane.org/gmane.comp.version-control.git/243940

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Jeff King]

On Wed, Mar 12, 2014 at 06:22:24PM +0100, Jens Lehmann wrote:

> > Let me know if you still think the hunk should be dropped there.
> 
> Yes, I think so. That spot uses memcmp() because ce->name may
> not be 0-terminated. If that assumption isn't correct, it should
> be replaced with a plain strcmp() instead (while also dropping
> the ce_namelen() comparison in the line above). But starts_with()
> points into the wrong direction there.

I think the length-check and memcmp is an optimization[1] here. But we
should be able to encapsulate that pattern and avoid magic numbers
entirely with something like mem_equals(). See my other response for
more details.

-Peff

[1] Getting rid of the magic number entirely means we have to call
    strlen(".gitmodules"), which seems like it is working against this
    optimization. But I think past experiments have shown that decent
    compilers will optimize strlen on a string literal to a constant, so
    as long as mem_equals is an inline, it should be equivalent.

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Duy Nguyen]

On Thu, Mar 13, 2014 at 12:22 AM, Jens Lehmann <Jens.Lehmann@web.de> wrote:
> That spot uses memcmp() because ce->name may
> not be 0-terminated.

ce->name is 0-terminated (at least if it's created the normal way, I
haven't checked where this "ce" in submodule.c comes from).
ce_namelen() is just an optimization because we happen to store name's
length if it's shorter than 4096, so there's no need to
strlen(ce->name) again.
-- 
Duy

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Michael Haggerty]

On 03/12/2014 03:06 PM, Quint Guvernator wrote:
> 2014-03-12 9:51 GMT-04:00 Duy Nguyen <pclouds@gmail.com>:
>> starts_with(..) == !memcmp(...). So
>> you need to negate every replacement.
> 
> My apologies--it doesn't look like the tests caught it either. I will
> fix this and submit a new patch.

It is very, very unlikely that you inverted the sense of dozens of tests
throughout the Git code base and the tests ran correctly.  I rather
think that you made a mistake when testing.  You should double- and
triple-check that you really ran the tests and ran them correctly.

Michael

-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/

Re: [PATCH] general style: replaces memcmp() with starts_with()

[Quint Guvernator]

2014-03-13 12:05 GMT-04:00 Michael Haggerty <mhagger@alum.mit.edu>:
> It is very, very unlikely that you inverted the sense of dozens of tests
> throughout the Git code base and the tests ran correctly.  I rather
> think that you made a mistake when testing.  You should double- and
> triple-check that you really ran the tests and ran them correctly.

It looks like HEAD was in the wrong place when I ran the tests. They
do not in fact pass.

Apologies,
Quint